TOKYO -- The disclosure by Sony Corp. that it won't have enough PlayStation 2 consoles for the Christmas season underscores the company's increasingly strained reliance on the videogame business, one of the most fickle industries.

Last week, Sony Computer Entertainment America Inc. said that it would halve -- to 500,000 -- the number of PlayStation 2 consoles it will ship at the machine's Oct. 26 debut in North America. The news shocked U.S. retailers, who had been expecting one of the biggest and most-lucrative...